Lighting of sports venues such as football fields, soccer fields, baseball fields, and tennis courts is challenging. Visibility is just one initial basic concern. Other concerns such as attainment of a specific level of illumination; distribution of light; uniformity of illuminance in different areas of the playing area; cost of lighting installations; life-cycle costs of lamps; luminaire efficiencies; beam patterns of the delivered illumination; effects of light trespass or spill light (e.g., light on neighboring areas); human perception of opposing players; revealing the spin of a ball and its path of travel; glare; and many other aspects of lighting all need to be considered.
Previously, the 1964/65 introduction of the metal halide lamp made the 1000 watt version a natural replacement for the 1500 watt incandescent lamp which had been the lamp of choice for sports lighting in the 1970's. By the 1980's, a 1500 watt metal halide lamp was introduced and it is now the most common lamp used for the illumination of sports facilities in North America. The National Electrical Manufacturer's Association (NEMA) published an Outdoor Floodlight Luminaire Designation document FA1-1973. This document lists the information about floodlight luminaire beams based on a series of “beam spreads”, “reflector effective area” and “minimum efficiencies” designated as a NEMA Types 1 through 7 (FIG. 1). This initial listing included information for floodlights using incandescent, mercury, fluorescent, and low pressure sodium lamps which were available in 1973. These beam type designations were adopted by the Illumination Engineering Society of North America (IESNA) (120 Wall Street, New York, N.Y. 10005), Sports Lighting Committee to identify which incandescent floodlights should be used for various sports lighting installations through the 1970's. With the introduction of the metal halide lamp in 1964/65, the NEMA Beam Type designation was also applied to metal halide floodlights but the efficiency designation was no longer used since metal halide luminaire beams were often not circular as was the case with the 1500 watt incandescent luminaire beams previously used in sports lighting.
While the currently used metal halide lamps and their utilized assemblies constitute an improvement over the relatively older incandescent lamps and assemblies thereof, they still suffer from various drawbacks. For example, the efficiency (amount of light delivered vs. amount of light produced of an installed family of metal halide lamps at a sports venue remains below 50%. In addition, a substantial portion of the playing area is not well modeled (e.g., depth perception is impaired, features of players and balls are obscured, and shapes and textures in general are not clear or easily discerned by the players) with the currently available installations. Currently known installations at sports venues also generate significant amount of spill light and glare. Many of these deficiencies create a need for a better system of lighting sports venues, from the amateur level all the way up to professional level.